At the event, Prince Charles noted his father's absence as he addressed the crowd.
"Only sad thing is that my father couldn't be here with us," Charles said. "If we shout loud enough, he might just hear us in hospital."
The crowd roared.
The concert is one of a series of events celebrating the queen's 60 years on the throne, the second-longest reign in U.K. history.
Prince Philip, whose 91st birthday is this Sunday, was hospitalized last December, that time for chest pains. The palace said Philip was treated for a blocked coronary artery and a successful "invasive procedure of coronary stenting" was performed.
Philip, the duke of Edinburgh, married Princess Elizabeth in 1947. She took the throne as queen six years later.